Pushups are awesome in their own right, but the statement that they can only do so much alone is so true!!! I weigh 165 pounds, however, I can do hundreds of one handed pushups. This is because I've literally done well over a hundred thousand pushups (both one handed and two handed) over the past four and a half years.
The only way I can maintain my mass is to add a backpack weighing at minimum 75 pounds, which during pushups will be pressing on my back on pressure points. BAD.
Free Weight training however can push you to your limits physically, while not doing anything to your body that you will feel un-naturally sore over tomorrow. I bench anywhere from 245 to 375 depending on the day, yet to bring my total "pushup weight" to anywhere close to 375, I'm going to be seriously messing up my back.
I am not a fan of the gym, instead, just take whatever gym membership fees you'd normally pay, and bow a bowflex!!! I've had mine for quite a while, and it has paid for itself, I still have the body, and I don't have to compete for the barbells for the smelly guy who thought he was something special pressing 150lbs...
Instead of trying to keep physically cut, all I really try to do is keep my chest arms and abs in fair shape. Not even a 6 pack abs, just flat. Then all I have to do is maintain. If you spend a ton of time in the gym, you are going to end up losing a lot of definition if you have to stop (injury or otherwise). With me, I can be dormant for a week, and I still look good.
To maintain, I spend 20 minutes twice a week on the bowflex, and do some hiking on my off days. If I have a hunt planned lets say on thursday, I do no hiking wednesday, and then hit the bowflex for forty minutes on thursday about three hours before I leave. It gives the muscles I have a little bit of short toning, and it also boosts the "I don't look good, I look damn good" mindset.